/**
 * Created by rain on 15/1/29.
 */
var GPS = {
    PI: 3.14159265358979324,
    x_pi: 3.14159265358979324 * 3000.0 / 180.0,
    delta: function (lat, lon) {
// Krasovsky 1940
//
// a = 6378245.0, 1/f = 298.3
// b = a * (1 - f)
// ee = (a^2 - b^2) / a^2;
        var a = 6378245.0;
        var ee = 0.00669342162296594323;
        var dLat = this.transformLat(lon - 105.0, lat - 35.0);
        var dLon = this.transformLon(lon - 105.0, lat - 35.0);
        var radLat = lat / 180.0 * this.PI;
        var magic = Math.sin(radLat);
        magic = 1 - ee * magic * magic;
        var sqrtMagic = Math.sqrt(magic);
        dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * this.PI);
        dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * this.PI);
        return {'lat': dLat, 'lon': dLon};
    },
//WGS-84 to GCJ-02
    gcj_encrypt: function (wgsLat, wgsLon) {
        if (this.outOfChina(wgsLat, wgsLon)) {
            return {'lat': wgsLat, 'lon': wgsLon};
        }

        var d = this.delta(wgsLat, wgsLon);
        return {'lat': wgsLat + d.lat, 'lon': wgsLon + d.lon};
    },
//GCJ-02 to WGS-84
    gcj_decrypt: function (gcjLat, gcjLon) {
        if (this.outOfChina(gcjLat, gcjLon)) {
            return {'lat': gcjLat, 'lon': gcjLon};
        }

        var d = this.delta(gcjLat, gcjLon);
        return {'lat': gcjLat - d.lat, 'lon': gcjLon - d.lon};
    },
//GCJ-02 to WGS-84 exactly
    gcj_decrypt_exact: function (gcjLat, gcjLon) {
        var initDelta = 0.01;
        var threshold = 0.000000001;
        var dLat = initDelta, dLon = initDelta;
        var mLat = gcjLat - dLat, mLon = gcjLon - dLon;
        var pLat = gcjLat + dLat, pLon = gcjLon + dLon;
        var wgsLat, wgsLon, i = 0;
        while (1) {
            wgsLat = (mLat + pLat) / 2;
            wgsLon = (mLon + pLon) / 2;
            var tmp = this.gcj_encrypt(wgsLat, wgsLon)
            dLat = tmp.lat - gcjLat;
            dLon = tmp.lon - gcjLon;
            if ((Math.abs(dLat) < threshold) && (Math.abs(dLon) < threshold)) {
                break;
            }

            if (dLat > 0) {
                pLat = wgsLat;
            } else {
                mLat = wgsLat;
            }
            if (dLon > 0) {
                pLon = wgsLon;
            } else {
                mLon = wgsLon;
            }

            if (++i > 10000) {
                break;
            }
        }
        return {'lat': wgsLat, 'lon': wgsLon};
    },
//GCJ-02 to BD-09
    bd_encrypt: function (gcjLat, gcjLon) {
        var x = gcjLon, y = gcjLat;
        var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * this.x_pi);
        var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * this.x_pi);
        bdLon = z * Math.cos(theta) + 0.0065;
        bdLat = z * Math.sin(theta) + 0.006;
        return {'lat': bdLat, 'lon': bdLon};
    },
//BD-09 to GCJ-02
    bd_decrypt: function (bdLat, bdLon) {
        var x = bdLon - 0.0065, y = bdLat - 0.006;
        var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * this.x_pi);
        var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * this.x_pi);
        var gcjLon = z * Math.cos(theta);
        var gcjLat = z * Math.sin(theta);
        return {'lat': gcjLat, 'lon': gcjLon};
    },
    distance: function (latA, logA, latB, logB) {
        var earthR = 6371000;
        var x = Math.cos(latA * Math.PI / 180) * Math.cos(latB * Math.PI / 180) * Math.cos(
                (logA - logB) * Math.PI / 180);
        var y = Math.sin(latA * Math.PI / 180) * Math.sin(latB * Math.PI / 180);
        var s = x + y;
        if (s > 1) {
            s = 1;
        }
        if (s < -1) {
            s = -1;
        }
        var alpha = Math.acos(s);
        var distance = alpha * earthR;
        return distance;
    },
    outOfChina: function (lat, lon) {
        if (lon < 72.004 || lon > 137.8347) {
            return true;
        }
        if (lat < 0.8293 || lat > 55.8271) {
            return true;
        }
        return false;
    },
    transformLat: function (x, y) {
        var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(
                Math.abs(x));
        ret +=
            (20.0 * Math.sin(6.0 * x * this.PI) + 20.0 * Math.sin(2.0 * x * this.PI)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(y * this.PI) + 40.0 * Math.sin(y / 3.0 * this.PI)) * 2.0 / 3.0;
        ret +=
            (160.0 * Math.sin(y / 12.0 * this.PI) + 320 * Math.sin(y * this.PI / 30.0)) * 2.0 / 3.0;
        return ret;
    },
    transformLon: function (x, y) {
        var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
        ret +=
            (20.0 * Math.sin(6.0 * x * this.PI) + 20.0 * Math.sin(2.0 * x * this.PI)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(x * this.PI) + 40.0 * Math.sin(x / 3.0 * this.PI)) * 2.0 / 3.0;
        ret +=
            (150.0 * Math.sin(x / 12.0 * this.PI) + 300.0 * Math.sin(x / 30.0 * this.PI)) * 2.0
            / 3.0;
        return ret;
    }
};